ZX80 Data Field
The data field is loaded to address 4000h, and it contains the whole system area, the basic program, and VARS area. Video memory is NOT included in ZX80 files.
The system area should contain proper data. The entry at 400Ah defines the end address (used to calculate the file length). Memory at 4028h and up may be misused for whatever purpose.
...

Sorry but I don't know whay you mean...

Try the attached program that should autorun on a real zx80 (someone can check?) and is running fine in both EightyOne and no$zx (v2), but not in ZEsarUX...

ZX80 Data Field
The data field is loaded to address 4000h, and it contains the whole system area, the basic program, and VARS area. Video memory is NOT included in ZX80 files.
The system area should contain proper data. The entry at 400Ah defines the end address (used to calculate the file length). Memory at 4028h and up may be misused for whatever purpose.
...

Sorry but I don't know whay you mean...

Try the attached program that should autorun on a real zx80 (someone can check?) and is running fine in both EightyOne and no$zx (v2), but not in ZEsarUX...tarun.o

This is on a real ZX80, graphics for the squares are wrong and no keys work and no gameplay.